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Velocities of RR Lyrae Stars in the Sagittarius Tidal Stream

A. Katherina Vivas·Robert Zinn·Carme Gallart
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Abstract

We have measured radial velocities and metallicities of 16 RR Lyrae stars, from the QUEST survey, in the Sagittarius tidal stream at 50 kpc from the galactic center. The distribution of velocities is quite narrow (std dev=25 km/s) indicating that the structure is coherent also in velocity space. The mean heliocentric velocity in this part of the stream is 32 km/s. The mean metallicity of the RR Lyrae stars is [Fe/H]=-1.7. Both results are consistent with previous studies of red giant stars in this part of the stream. The velocities also agree with a theoretical model of the disruption of the Sagittarius galaxy.

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A. Katherina Vivas, Robert Zinn, Carme Gallart. 2003-09-12. Velocities of RR Lyrae Stars in the Sagittarius Tidal Stream. https://arxiv.org/abs/astro-ph/0309365

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